### Lesson Summary

### Overview

The number 100 is pretty large. Or is it? Just how big is 100? How much space does 100 take up? In this lesson, students think about how to measure 100. In the process, they learn about the benefits of using standard units to measure length.

### Objectives

- Understand the benefits of using standard units to measure length

### Grade Level: K—2

### Suggested Time

- One to two class periods

### Multimedia Resources

- 100's Day Video

### Materials

- Various objects in sets of 100 that can be laid flat and used to measure length (for example, paper clips, pencils, pieces of paper, etc.). If possible, you may want to include several colored objects of each type to serve as temporary measurement markers. (See Step 3.)
- Index cards
- Masking tape

### Before the Lesson

- Gather all materials.
- Arrange the classroom so that there is sufficient space for student pairs to measure 100 across the room.

### The Lesson

### Part I: How To Measure 100

1. Tell students that they will be exploring how to measure to 100. Ask them to begin the lesson by sharing their ideas about the number 100. How big is 100? How would you measure 100? What kind of object or structure might be 100 big or 100 long?

2. Show students the 100's Day QuickTime Video. Discuss with students some of the different ways that the students in the video measured to 100. Then have them reflect on the same questions they considered before they viewed the video. How big is 100? How would you measure 100? What kind of object or structure might be 100 big or 100 long?

### Part II: Let's Measure 100!

3. Divide students into pairs. Tell them that you are planning to put up a temporary wall to separate off one section of the classroom. You want the wall to be 100 long. Ask students to use one of the materials that you have provided, or some part of their body—such as hands or feet—to mark off how long the wall will be. All pairs should start from the same place (a common wall) to measure the space needed for the new wall.

You may want to provide students with a temporary method for keeping track of their count. For example, if they are using paper clips, they can use a colored paper clip to mark every 10 or 25 in the count. If they are using their hands or feet, they can use small pieces of masking tape or colored sticky notes to mark every 10 or 25 measurements.

After each pair has lined up 100 items, give them a piece of masking tape to mark their end point. The temporary markers can be removed at this time, so the only markers that remain are the end points. Have the pairs write down on an index card which 100 materials they used and then tape a sample or picture of this object (their unit of measure) onto the card. They can then attach the index card to their masking tape on the floor.

4. Bring the class back together and have everyone look at the different measurement marks on the floor. Discuss with students what they notice about the marks. Students should notice that 100 can look very different depending on what objects or units you use. Then discuss the following questions:

- What would happen if you asked someone else to measure 100 for a new wall? Would they reach the same spot that you did?
- How would you tell another group to measure 100 so that they would reach the exact spot that you did?
- What if they didn't have the same materials (or had different-sized hands or feet)?

Lead the discussion to the idea that agreed-upon "units" of measure are important because they tell you what a quantity represents. A length of 100 (or any number) is meaningless unless you know what the unit of measurement is. And in order to have that unit be useful to others, it is important that it is the same for everyone who uses it, whether it is inches and feet or centimeters and meters.

### Check for Understanding

Tell students to imagine that they will be helping you organize a big 100's day celebration to take place in your classroom. There will be decorations, cake, and games, but they will need to plan carefully to make sure everything is just right. Ask students to write down or draw the answers to the following questions:

- What kinds of things (length of the table, length of the wall for a banner) might you need to measure to prepare for the party? List or draw three to five things you could measure.
- What units would you use to measure each of the items on your list?

Note: Depending on your students' understanding of different measurement concepts, you may want to limit their focus to measuring the length of objects or structures, or expand it to include area and/or volume. Let students know what their focus will be before they respond to the questions.